package ClassB;
use Moose;
extends 'ClassA';

has '+param2' => (default => 'PARAM2-CLASSB');

around FOREIGNBUILDARGS => sub {
    my $orig = shift;
    my $class = shift;
    return $class->$orig(param1=>'PARAM1-CLASSB',@_);
};

##</code><code>##

package ClassA;
use Moose;
use MooseX::NonMoose;
extends 'aNonMooseClass';

has 'param2' => ( isa=>'Str', builder => '_build_param2');

sub FOREIGNBUILDARGS {
    my $class  = shift;
    my %args   = @_;
    my $param1 = exists $args{param1} ? $args{param1} : $class->_build_param1;

    return ( $param1 );
}

sub _build_param1 {
    return 'Default param1 in class A';
}

sub _build_param2 {
    return 'Default param2 in class A';
}


package ClassB;
use Moose;
extends 'ClassA';

sub _build_param1 {
    return 'PARAM1-CLASSB';
}

sub _build_param2 {
    return 'PARAM2-CLASSB';
}